Heterocyclic quaternary salts,sensitizing dyes,and photographic emulsions made therefrom



United States Patent US. Cl. 260240.1 3 Claims ABSTRACT OF THE DISCLOSURE Thiazoline bases having an aryl substituent in the 5-position which serve as intermediates for the preparation of cyanine, carbocyanine, merocyanine, and related photographic sensitizing dyes and styryl dyes. The bases have the formula:

| C 2 C-CHa R1 where R is alkyl or aryl and R is H, alkyl or aryl. New dyes are disclosed. The cyanine dyes are useful in photographic color emulsions and cause no change in the sensitivity spectrum and no bathochromatic shift in the sensitivity maximum and preserve selective sensitization in the orthochromatic domain.

The present invention relates to a new heterocyclic quaternary salts containing a reactive methyl group to sensitizing dyes made therefrom and to spectrally sensi tized photographic emulsions of silver halide containing the novel dyes.

It is well known that cyanine dyes, containing an unsubstituted thiazoline ring, are particularly useful for the selective, orthochromatic sensitization of silver halide emulsions in the short wave-length region. This results in the intensive sensitization and improved sensitivity particularly of silver chloride emulsions used in the manufacture of photographic papers and graphic arts films, this sensitization affecting the blue and the blue-green regions of the spectrum (cf. P. Glafkides, Photographic Chemistry, vol. I I, p. 824). Photographic silver halide layers sensitized in this manner have a wide margin of dark room safety and extensive freedom from residual stain. v

However, owing mainly to their tendency towards diffusion, thiazoline dyes derived from unsubstituted thiazoline rings are of little use in various other types of emulsions such as those containing coupling agents or other additives which impair the sensitization. In layers containing coupling agents, stabilizers, or other emulsion additives, these dyes are partly displaced from the grains, or the portion that is not directly adsorbed on the grains diffuses to the adjacent layers of emulsion or additives and (where R is an alkyl or an aryl group and R is an alkyl or an aryl group, or a hydrogen atom, and R is an alkyl, carboxyalkyl or sulfoalkyl group) exert an outstanding and highly selective short-wavelength sensitization, which is superior to that of the well-known unsubstituted sensitizers of this type since they have a higher resistance to diffusion and they ensure a higher sensitivity. Suitable alkyl groups include methyl, ethyl and isopropyl and suitable aryl groups include phenyl and tolyl.

It is known that the tendency of cyanine dyes to diffuse to adjacent layers in photographic color films can be reduced by substitution by bulky unsaturated groups, e.g., phenyl groups. However, the introduction of substituents, particularly phenyl groups, for rendering the substance more stable to diffusion invariably causes an appreciable change in the original sensitivity spectrum generally causing a bathochromic shift in the sensitization maximum or in the long-wavelength limit of sensitization. This shift in the sensitization maximum or in the sensitization limit toward the longer wave-length region has a highly undesirable effect when a selective sensitization or greater darkroom safety is required. In other cases, in which bulky substituents are used for increasing the diffusion stability of sensitizers, both the color and the general sensitivity are reduced as compared to the sensitivity obtained with the unsubstituted dyes, or the contrast of the developed image is lower.

It was, therefore, surprising to find that the presence of bulky unsaturated substituents in the 5-position of the thiazoline nucleus of the cyanine dyesof the present invention causes practically no change in the sensitivity spectrum and particularly no bathochromic shift in the sensitivity maximum, enabling one instead to preserve fully the selective sensitization in the orthochromatic domain and the darkroom safety of the photographic material thus sensitized.

It was also surprising to find that the thiazoline dyes of the present invention, containing bulky aryl substituents in the 5-position, cause no reduction in the general and the color sensitivity of the photographic material sensitized in this manner, i.e. no reduction with respect to that achieved by unsubstituted thiazoline dyes, but often cause instead a better general and color sensitivity than that obtained with the known thiazoline dyes.

Thiazoline bases having an aryl substituent in the S-position, which serve as intermediates in the manufacture of the dyes, correspond to the general Formula II materials, this method proceeding via the following steps and leading to good yields:

IIi E2 1 NH l Ha/Raney-Ni The bulky aryl groups introduced in this manner in the thiazoline ring in the -position and leading to an increase in the diffusion stability of the sensitizers are exemplified by the following groups: 4-methoxyphenyl, 4-ethoxy-phenyl, 4-phenoxyphenyl, 3,4-dimethoxyphenol, 3,4-diethoxyphenyl, 4-methoxydiphenyl, and 3-methyl-4- methoxyphenyl.

The substances of the present invention are also superior to dyes containing unsubstituted thiazoline rings in that the latter are very soluble, and therefore very diflicult to isolate, as a result of which they can be obtained only in low yields.

The resulting new thiazoline bases can be converted into the reactive heterocyclic 2-methyl alkyl or aralkyl quaternary salts by methods commonly employed in the chemistry of cyanines, e.g. by reacting them with an alkyl or aralkyl salt forming compound, e.g., ethyl iodide or other alkyl halides, benzyl chloride, methyl or diethyl sulfate, w-halocarboxylic acids, sultones and alkyl-p-toluene sulfonates, e.g., methyl or ethyl-p-toluene sulfonate.

The resulting heterocyclic quaternary salts of the invention may be represented by the formula:

(where R is an aryl or an alkyl group, R is an alkyl or an aryl group, or a hydrogen atom, R is an alkyl, a carboxyalkyl, or a sulfoalkyl group, and X" is an anion such as Cl, Br, I, 010,, and SO C H CH can be converted into the required sensitizing dyes by the common processes, though the preferred route is via the alkaline condensation using strong tertiary bases, e.g., pyridine, piperidine, dialkylamines, etc.

Symmetrical trimethinecyanines containing the S-arylsubstituted thiazoline ring of the present invention can be prepared, e.g., from the quaternary salts of the general Formula III, by reacting the latter in the Well-known manner With orthoesters, e.g., triethyl orthoformate, triethyl orthoacetate, or triethyl orthopropionate in pyridine.

Unsymmetrical cyanine dyes are obtained by condensing the quaternary salts of the general Formula III with a cyclic ammonium salt of the general Formula IV O 0 CH3 (IV) where R is an alkyl, a carboxyalkyl, or a sulfoalkyl group and Z is an atom needed for the closure of a five-membered ring. This condensation is carried out in pyridine or alcohol, in the presence of a tertiary amine such as triethylamine. The cyclic ammonium salts suitable for this reaction are exemplified by 2-fi-acetanilidovinylbenzoxazole ethiodide, Z-fl-acetanilidovinylbenzselenazole ethiodide, and 2-,8-acetaniliodvinyl-p-napthothiazole ethiodide.

Merocyanines, containing according to the present invention at least one thiazoline ring carrying an aryl substituent in the 5-position have been found particularly suitable. They correspond to the general Formula V where Y is oxygen, sulfur, or an N-alkyl, .or an N-aryl group, R is an alkyl or an aryl group, R is an alkyl or an aryl group, or a hydrogen atom, R is an alkyl, a carboxyalkyl, or a sulfoalkyl group, and R is an alkyl group. These compounds can be prepared by the reaction of quaternary salts of the general Formula III with the ,G-acetovinyl derivatives of ketomethylene compounds represented by the general Formula VI 23:0 i OCH;

a (VI) where Y and R denote the same groups as in the general Formula V.

In Formulae (II)-(VI) inclusive, specific alkyl radicals have 1 to 4 carbon atoms and include methyl, ethyl, isopropyl and butyl. Specific aryl radicals are phenyl and tolyl.

Furthermore, polynuclear complex merocyanines can be prepared by quaternizing with alkylating agents the simple merocyanines of the general Formula V obtained from the quaternary salts of the general Formula III, this quaternization being followed by reacting the resulting merocyanine quaternary salts with reactive 2- methylcyclo-ammonium salts in the Well-known manner. This method is also suitable for the preparation of, e.g., complex trinuclear merocyanines containing twice in the dye molecule the thiazoline ring carrying an aryl substituent in the 5-position, in accordance with the present in- 6 vention. These compounds a re also particularly suitable, thiazolinium iodide with 7.7 g. of 5-acetanilidomethyl-3- and they correspond to the following general formula: ethylrhodanine in 25 ml. of water-free pyridine and 2.5 ROQCH-S R1 o5: /(IJ=CHCH=(IJSIB' i([lH-OR 1 1 O=G\ /C=CH /CH2 Iih R2 III 1? l R; R3 x (VII) where Y is oxygen, sulfur, or an N-alkyl, or an N-aryl ml. of triethylamine. The reaction mixture was refluxed group, R is an aryl or an alkyl group, R is an alkyl or for 35 mm., cooled, and then poured onto 2 l. of a dilute an aryl group, or a hydrogen atom, R is an alkyl group, solution of potassium iodide. An oily substance separated R is an alkyl, carboxyalkyl, or sulfoalkyl group, and X out at the bottom, and the supernatant liquid was deis ananion such as Cl, Br, I, C10 or SO C H CH canted. The oily dye was again treated with methanol/KI Suitable alkyl groups include methyl, ethyl and isopropyl solution, and separated out again. After this, it was reand suitable aryl groups include phenyl and tolyl. peatedly treated with hot methanol. As a result of these The styryl dyes, which, according to the present invenoperations, the oily substance was converted into the solid tion, contain at least one thiazoline ring carrying an aryl form, and was then recrystallized to obtain it in the pure substituent in the 5-position, can be prepared by reacting state. Yield 2.4 g., M.P. l63-l65 C. (Decomp), abthe thiazoline quaternary salts of the general Formula sorption maximum in methanol: 485 m III with aromatic aldehydes, particularly 4-dimethylaminobenzaldehyde, 4-dimethylaminonaphthaldehyde, or Examp 1e 2 4-di-(fi-hydroxyethyl)aminobenzaldehyde, in the presence A SeIlSifiZer 0f F u a 2 of acid-binding condensing agents such as piperidine or triethylamine. i i C JHs 1H3 For the spectral sensitization of photographic emulsions, the thiazoline dyes of the present invention are O(l3 added to the emulsion before coating, the actual manner T of their introduction being simple and well-known to ex- 02115 perts. The dyes are generally added in the form of a solution to the emulsions after the post-digestion and prior to coating, methanol being a suitable solvent in most cases. However, the addition of the sensitizers can also be carried out during the post-digestion of the emulsion.

The concentration of the dye in the emulsion can vary within wide limits depending on the required action. Thus, one may use about 5 to 100 mg. of sensitizer per kg. of the emulsion. However, the sensitizer concentration depends also on the type of the emulsion used. In the case the unsensitized materafl' of many sensitizers of the present invention, however, a The intermediate very small amount (20 to 25 mg. per kg. of emulsion) of the sensitizer is sufficient for the optimal sensitization of silver halide emulsions. In the case of emulsions containwas added in an amount of 25 mg. per kg. of emulsion to a photographic emulsion of silver bromide and silver iodide containing 4 to 7 mole-percent of the iodide. This resulted in a sensitization reaching from the sensitivity of the emulsion to 590 my which showed a steep descent on the long-wavelength side of the sensitization domain. The material sensitized in this manner exhibited practically no residual coloration and a higher general sensitivity than I 1 ing dye-coupling agents, on the other hand, optimum sens sitization is reached only with a somewhat higher dye I I 19 concentration, e.g., 40 to 80 mg. of dye per kg. of the @2115 Cast emulslon' required for the preparation of the sensitizers used in Examples 1 and 2 was obtained in the following manner: Step (a)w-Amino-4-ethoxyacetophenone hydrochloride C Powdered anhydrous aluminum trichloride (1230 g.) 1 was introduced stepwise and with stirring into 2.7 l. of

C=CH OH:C-? freshly distilled nitrobenzene. Care was taken to exclude N 0 all moisture. After complete dissolution of the aluminum (355 trichloride, 460' g. of aminoacetonitrile hydrochloride I were added stepwise and with stirring, the liberated reac- 2 5 tion heat being educted by external cooling. To the rewas added in an amount of 25 mg. per kg. of emulsion sulting homogeneous solution were then added 605 g. of

Example 1 A sensitizer of Formula 1 to a photographic emulsion of silver chloride containing phenetole, and the mixture was stirred for 30 min. A 30 mole-percent of bromide. This resulted in a sensitizastream of dry hydrogen chloride was passed for 8 hours tion reaching from the sensitivity of the emulsion to about into the deep-colored mixture. The reaction mixture was 595 me, which showed a maximum at 560 mu and a then poured, with energetic stirring, into water in such steep descent on the long-wavelength side of the sensitiZaa manner that the hydrolysis temperature was C. The tion domain. The material sensitized with this sensitizer solution was stirred until it reached room temperature. exhibited a clearly higher general sensitivity than the ma- The crude aminoketone hydrochloride was filtered off at terial which Was basically th Same, but contained an the pump, washed with acetone and ether, and recrystalanalogous sensitizer instead of the sensitizer carrying a lized from methanol, Yield 295 g M.P, 212 C,

p-alkoxyphenyl substituent. On the other hand, the sen- 70 S b -Acet lamino-4-ethox aceto henone sitivity maximum and the sensitivity limits were not differ tep w y y p ent from those of the sensitizer carrying no p-alkoxyw-Amino-4-ethoxyacetophenone hydrochloride (245 g.) phenyl substituent. prepared in step (a) was well ground with 150 g. of an- The sensitizer used in this example was prepared by rehydrous sodium acetate, and the mixture was made to react acting 9.4 g. of 2-methyl-3-ethyl-5-(4-ethoxyphenyl)-A2,3- by introducing it into a solution of ml. of acetic anhy- 7 8 dride in 245 ml. of glacial acetic acid. After being heated gether with steep fall of sensitivity at the long-wave-' at 80 C. for 2 hours on oil bath (in the absence of moislength side of the sensitivity domain. The developed, ture), the reaction mixture was poured into 4 l. of water. fixed, and dried material was found to be fully devoid The solid precipitating out was filtered off at the pump of any residual coloration and exhibited a higher general and redissolved in chloroform. The chloroform solution and color sensitivity than the material prepared similarly,

was shaken with dilute HCl and washed with water. The 5 but with an analog instead of the merocyanine containsolution was dried and the solvent evaporated giving the ing the thiazoline nucleus carrying a p-ethoxyphenyl reacetyl compound in the form of a white crystalline mass. sidue in the 5-position. The sensitization region and the After recrystallization the yield was 175 g., M.P. 138 C. maximum did not differ from those of the analog.

Step (c)N-acetyl-2-(4-ethoxyphenyl)ethanolaminerl Exam le 4 Omega acetylamine 4 ethoxyacetophenone (175 g.) A sensitizer of Formula 4 prepared in step (b) was dissolved in l l. of methanol and was added in an amount of 60 mg. per kg. of an emulsion hydrogenated at 60 C. and 60 atm. with hydrogen and of silver bromide and silver iodide containing 7 mole- Raney nickel. The catalyst was removed and the methapercent of I and a pyrazolone derivative as a dye-coupling 1101 was distilled off giving 160 g. of N-acetyl-2-(4- agent. This resulted in a green sensitization up to 595 ethoxyphenyl) ethanolamine-l in the form of white my, showing a maximum at 575 me. This sensitization crystals M.P. 95 C. The product could be used without is suitable for the magenta layer. further purification. The following process was used to prepare the senstep (d)2'methy1-5'(4-ethoxyphenyl)thIaZOhne-AZ nucleus carrying a p-ethoxyphenyl residue in the 5-posi- N-acetyl-2-(4-ethoxyphenyl) ethanolamine-l 160 g.) i

P p in p Was made to react With Of The merocyanine sensitizer (8.0 g.) of Example 1 diphosphorous pentasu fid y heating of the miXtuTewas dissolved in 20' ml. of hot chlorobenzene. This was After a homogeneous reaction mixture has been formed, f ll d by h dropwise addition of 2.4 g. of dimethyl the reactants were heated for 2 hours a C- With sulfate dissolved in 10 ml. of chlorobenzene and by re- Stiffihg- When the reaction had reached Completion, all fluxing of the mixture for 15 min. The reaction mixture thfi Volatile Products were removed y Vacuum distillawas cooled, treated with ether, and allowed to stand for tion at 13 C-/ -5 mm. This gave 65 of a crude several hours. The supernatant liquid was decanted and product, which was dissolved in ether and freed from 12.8 g. of an oily substance were obtained. acids over fused sodium hydroxide. A second fractiona- Th l il d t were removed fro h il tiOIl under Vacuum gavfi Of P y under vacuum, and the oil was dissolved in 40 ml. of dry ethoxyphenyl)-thiazoline-A2 distilling over at 144-147 idi together i h 73 f 2- 1 3- 1 5 4 C./ 0.2 mm. Hg. ethoxyphenyl)-A2,3-thiazolinium iodide. This mixture was Step (f) 2 methy1 3 ethy1 5 (4 ethoxyphenyl) 45 refluxed for 15 min. After the reaction had reached completion, the crude dye was precipitated from the reacth'azolinium-AZ iodide 1 t1on mixture with ether and freed from the unreacted The thiaZ base 8-) P p 1h p merocyanine by repeated treatment with dimethylformheated for 8 hours to 110 C. in a glass autoclave w1th amide and ether. It was fi ll obtained in the pure 32 g. of ethyl iodide. {after the quaternlzatlon had reached State by treatment f the di th lf a id di completion, the Teactloh mlxture cooled and P with a solution of sodium perchlorate. The dye exhibited sulting solid product was triturated in acetone. Yield 56 in an alcoholic Solution an absorption maximum at 537 g., M.P. l3l132 C. (decomp.). mlh

In the case not described above, the preparation of Example 5 the sensitizer dye of Examples 1 and 2 from the quaternary salt step (f) was carried out in accordance with the usual methods employed in the chemistry of cyanines.

A dye of the following formula 30 sitizer of Example 4, containing a trinuclear thiazoline Example 3 omQ-on-s /CH2 A sensitizer of Formula 3 60 CHaO (1E2 %OCH=OHN\ t Ce C2H5 1 was prepared by refluxing for 20 min. 3.9 g. of Z-methyl- CZHEO' O('3H IS I 55 3-ethyl-5-(3,4-dimethoxyphenyl)-A2,3-thiazolinium iodide CH2 G=OHCH=C--N and 1.5 g. of 4-dimethylaminobenzaldehyde in 25 ml. of.

0:0 (llzs acetic anhydride. Cooling of the reaction mixture led to separation of the crude crystalline dye, which was filtered CZHE off, washed with ether, and recrystallized from methanol. 0 11 The resulting dye is soluble in water and can be bleached in photographic developing baths. Its absorption was added in an amount of 25 mg. per kg. of emulsion maximum (478 m in an alcoholic solution does not to a photographic emulsion of silver bromide and silver differ from that of the dye carrying no aryl substituentiodide containing 4-7 mole-percent of the emulsion to in the 5-position. A method analogous to that used for about 565 m and showing a maximum at 540 m tothe preparation of the 2-methyl-3-ethyl-5-(3,4-dimethoxyphcnyl)-A2,3-thiazolinium iodide, the starting compound R is alkyl of 1-4 carbons, requlred for the Preparanon of a R is alkyl of 1-4 carbons, carboxyalkyl, or sulfoalkyl of Examp 1e 6 1-3 carbons, and A sensitizer of the following formula I 02 3 CzHs was obtained by reacting the reactive quaternary salt of xis a Cl, Br, I, C10 or SO C H CH anion;

l 1 CH2 G-CH 1 N 9 R2 (152115 wherein R, R and R have the same values as in the two in the well-known manner with triethyl orthoacetate in a preceiding formulae, and is Y P Y suitable solvent in the presence of triethylamine as a basic 4 E (beta hydroxyethyl)ammophenyl- 0T 4 dlmeth' condensing agent. The above quaternary salt is prepared ylammonaphthyl'i and from o-cresol methyl ether and w-aminoacetonitrile hydrochloride in a manner similar to that described in Example R 0 CH S f 6B 1. The resulting dye was isolated and purified. It showed om (]JCH=CCH=C=(L= )nlN-R2 an absorption maximum at 465 nm in an alcoholic solu- 9 tion.

This sensitizer was added in a quantity of 60 mg. per R2 kg. of cast emulsion to a photographic emulsion of silver wherein 1 and 2 have the Same Values as in the P chloride and silver bromide containing 30 mole percent i g ll a n t Case Of symmetrical dyes is H, CH or C H and in the case of unsymmetrical dyes is H, L is a methine group, n is 0 or 1, x is a Cl, Br, I,

of bromide. This resulted in a sensitization reaching up to 540 m and showing a maximum at 495 m The embodiments of the invention in which an exclusive C10 0r SO C H CH anion, and Z is the atoms necessary property or privilege is claimed are defined as follows: to complete a benZOXaZOle benlothialole, llaphthiazole,

1. A cyanine dye containing at least one thiazoline ring benzselenazole nucleus or a nucleus of the formula substituted in the 5-position selected from the dyes of the 40 formulae: ROC CHS R] \N/ 0(: (IJS R I wherein R, R and R have the same values as in the R2 N preceeding formulae.

2. A merocyanine dye of the formula:

wherein a Y is oxygen, sulfur, N-alkyl of l-4 carbons, phenyl or 0 tolyl, g3 /C=CH-CR4=CY R is alkyl of 1-4 carbons, phenyl or tolyl, N 0=0\ /o=s R is hydrogen or an alkyl of 1-4 carbons, phenyl or tolyl N or alkoxy of l-2 carbons,

R is an alkyl of 1-4 carbons, carboxyalkyl, or sulfoalkyl R3 of 1-3 carbons, where R is an alkyl of 1-4 carbons, and Y is oxygen, sulfur, N-alkyl of 1-4 carbons, phenyl or R is hydrogen, methyl or ethyl; tolyl,

G-t n 1 CH2 C=CHCH=CY SCH-OR X B1 i 1Y1 0=0\ /O=CHC\ 0H2 R2 N \N Ra a where R is alkyl or 1-4 carbons, phenyl or tolyl, R is hydrogen Y is oxygen, sulfur, N-alkyl of 1-4 carbons, phenyl or or an alkyl of 1-4 carbons, phenyl or tolyl,

tolyl R is an alkyl of 1-4 carbons, carboxyalkyl, or sulfo- R is an alkyl of 14 carbons, phenyl or tolyl, alkyl of 1-3 carbons,

R is hydrogen, alkyl of 1'4 carbons, phenyl or tolyl or R is an alkyl of l-4 carbons, and alkoxy of 1-2 carbons, R is hydrogen, methyl or ethyl.

3,507,859 11 12 3. A polynuclear complex merocyanine dye of the formula:

10 References Cited UNITED STATES PATENTS 2,177,403 10/1939 Brooker 260240.4 2,186,624 1/1940 Brooker 260240.4

5 OTHER REFERENCES Derwent Soviet 'Inventions illustrated, Group 3, page 3 (May 1966), (abstract of Russion Patent 174,065).

where Y is oxygen, sulfur, N-alkyl or 1-4 carbons, pheny1 0r 1 tolyl R is an alkyl of 1-4 carbons, phenyl or tolyl, R is hydrogen, alkyl of 1-4 carbons, phenyl or tolyl, R is alkyl of 1 4 carbons, 20 JOHN D. RANDOLPH, Primary Examiner R is alkyl of 1-4 carbons, carboxyalkyl, 0r sulfoalkyl CL of 1-3 camnsand 96-406; 260240.4, 240.8, 240.9, 240.65, 306.7, 561,

x is a Cl, Br, I, C10 or SO C H CH anion. 570.5 

